Solenoid type electromagnetic pump



May 26, 1970 AKIRA TOYODA 3,514,228

SOLENOID TYPE ELECTROMAGNETIC PUMP Filed Jan. 15, 1968 FIG.I.

9 N O 2 0 IO\ p 2 7 II 8 ii!!! A INVENTOR.

United States Patent 3,514,228 SOLENOID TYPE ELECTROMAGNETIC PUMP AkiraToyoda, 13-16 4-chome, Minamimagone, Ohta-ku, Tokyo, Japan Filed Jan.15, 1968, Ser. No. 697,821

Int. Cl. F041) 17/04 US. Cl. 417-416 1 Claim ABSTRACT OF THE DISCLOSUREA solenoid type electromagnetic pump comprising solenoid typeelectromagnetic plungers including an electromagnetic lunger and adischarge plunger an upper and lower spring operatively connected to theplungers for causing both of the plungers to be in contact with eachother and a semi-wave rectifier to which the solenoid coil is connectedin series.

The present invention relates to a solenoid type electromagnetic pump,to be used for various purposes.

In general, the change of voltage current of an A-C power source forms aperiodic wave-type sine curve, and in case this A-C is supplied to themagnetic coil, the size of the absorption force generated in theelectromagnetic plunger is caused to change corresponding to thewavetype, and the direction of the absorption force is constantnotwithstanding the positive or negative current.

The number of interrupting frequencies of the absorption force, in thecase of conventional A-C current, is as follows:

Power source frequency Perior of the absorption force 50 00/ second 10000/ second 6000 00/ minute 60' 00/ second 120 00/ second 7200 00/ minuteThe frequency of pump operation of an ordinary electromagnetic pump tobe operated by a conventional A-C power source is determined by thefrequency of the power sources, and the frequency of the pum operationin the frequency of the power source SOw/second, 6000/ second arelOOoo/second and 120oo/S6C0nd, respectively.

In such high speed periods, the switching operations of tthe inlet checkvalve and the discharge check valve of the pump and the reciprocaloperation of the electromagnetic plunger and the discharge plunger arenaturally limited by the resistance of the fluid flowing in the pump andthe frictional resistance of the sliding portion in the pump. Therefore,the absorption by the inlet check valve and the discharge check valve,and the discharge efliciency become extremely low, and the period of thereciprocating movements of the electromagnetic plunger and dischargeplunger are greatly limited to a short time. The stroke thereof becomesshort, resembling vibration, and an improvement of the pump efficiencycannot be achieved.

It is an object of the present invention to provide an extremely highperformance electromagnetic pump capable of eliminating uneven operationdue to frictional resistance caused in the movement of theelectromagnetic plunger and the discharge plunger.

With the above and other objects in view which will become apparent inthe following detailed description, the resent invention will be clearlyunderstood in connection with the accompanying drawing, in which:

FIG. 1 is an axial cross-sectional view through an embodiment of asolenoid type electromagnetic pump designed in accordance with theinvention; and

FIG. 2 is an electrical circuit diagram of the embodi? ment of FIG. 1.

Referring now to the drawing, an electromagnetic pump in accordance withthe present invention includes a solenoid coil 1 of a solenoid typeelectromagnetic pump which 3,514,228 Patented May 26, 1970 is connectedin series to a half-wave rectifier F, as shown in FIG. 2, and byutilizing the half-wave of a conventional A-C power source the frequencyof movement of the electromagnetic pump per unit time is made equal tohalf of the frequency of movement thereof per unit time where thecommercial A-C power source is not rectified with a half-Wave. As shownin FIG. 1, an electromagnetic plunger 2 is located in the centralportion of the solenoid coil 1 and operates reciprocally along thevertical axis of the solenoid coil by means of the magnetic force. Adischarge plunger 3 is provided carrying the suctioned fluid. Bothplungers are formed as separate units and are arranged in contact. Alsoboth plungers are caused to operate in a condition where they arecompressed between a supporting spring 9 disposed in the upper ortion(hereinafter referred to as an upper spring) and a spring 4 for the backstroke of the discharge plunger 3 disposed in the lower portion(hereinafter referred to as a lower spring).

As shown in FIG. 1, the solenoid 1 of the solenoid type electromagneticpump of the present invention is connected in series to the half-waverectifier F and the conventional A-C-current is half-wave rectified andsupplied to the solenoid coil 1. The reciprocal movements of theelectromagnetic plunger 2 and discharge plunger 3 become 5000/ secondand 6000 second, whereby the aforementioned drawbacks of the prior artare eliminated, and the absorption discharge efficiency of the inletcheck valve 6 and the discharge check valve 8 are improved therebymaking the reciprocal stroke of the electromagnetic plunger 2 anddischarge plunger 3 longer. Accordingly an improved high performancepump is obtained.

In the solenoid type electromagnetic pump as shown in FIG. 1, when theA-C is supplied from the power source, the half-wave current rectifiedin the half-wave rectifier F is caused to flow to the solenoid coil 1 ofthe pump proper P, intermittently. Therefore the magnetic forcegenerated in the solenoid section is also caused to repeatintermittently.

When the magnetic force is generated between the solenoid coil 1 and theelectromagnetic plunger 2 which is in contact with the discharge plunger3 under pressure from the upper spring 9 and the lower spring 4, theelectromagnetic plunger 2 is absorbed in the lower direction.Simultaneously the plunger 3 is caused to move downwardly. When themagnetic force ceases, the electromagnetic lunger 2 and the dischargeplunger 3 are returned rapidly to the original position by the action ofthe lower spring 4. Fluid is absorbed into a plunger chamber 7 through ahose H, a tank 5 and an inlet side check valve 6 from a liquid tank T bymeans of the vertical reciprocal movements of both plungers 2 and 3.Then the fluid is condensed, and discharged outside through a dischargecheck valve 8 by maintaining the specific pressure. The pump operationis effected by repeating the foregoing functions.

Therefore, in order to operate the electromagnetic plunger 2magnetically and efficiently, the cross-section thereof is limited bythe input of the solenoid coil 1. Where a plunger serving both as anelectromagnetic plunger and a discharge plunger, is used, it isextremely difficult to obtain the optimum discharge plungercrosssectional area for obtaining simultaneously the desired dischargepressure.

On the other hand, according to the present invention, anelectromagnetic plunger 2 having the most suitable cross-sectional areafor the input of the solenoid coil 1 can be selected. Also it .ispossible to select separately and independently, the discharge plungerhaving a crosssection most suitable for the required discharge pressureand suitably balanced with the magnetic force.

Furthermore, the discharge plunger 3 prevents leakage of the compressedfluid in order to produce the pressure by minimizing the gap between thecylinder wall 11 of the plunger chamber 7 and the discharge plunger. Onthe other hand, the electromagnetic plunger 2 must avoid friction withthe inner wall of a plunger case when the electromagnetic plunger 2 iscaused to effect vertical and reciprocal operation. Therefore the gap isdesired to be larger than the gap formed between the discharge plunger 3and a cylinder wall 11, and also the electromagnetic plunger 2 in itsvertical and reciprocal movement. It is extremely difiicult to cause theplunger 2 to operate without any eccentricity to the geometricalvertical axis of the center of the solenoid which is theoretically themagnetic center line, and actually the plunger 2 is caused to slidablyoperate toward one side of the inner wall of the plunger case 10 whichside is olf the axis of the center line, and where the electromagneticplunger and discharge plunger are mechanically coupled or theelectromagnetic plunger of is of its integral construction, thedischarge plunger is received with high frictional resistance by theside pressure with the cylinder wall 11, and therefore the smoothoperation of the plunger cannot be obtained.

With the present invention, the electromagnetic plunger 2 and thedischarge plunger 3 are constructed as a separate unit, and with respectto the movements of both plungers, uneven operation due to frictionalresistance, that is, the drawback mentioned in the foregoing, iseliminated, whereby a high performance electromagnetic pump is provided.

What should be specifically noted here is the outstanding effect derivedfrom the combination of the features of: an electromagnetic plunger 2disposed in a plunger casing 10 through the center of the axial core ofthe solenoid coil 1 and arranged to reciprocate therein, and a dischargeplunger 3 adapted to reciprocate slidingly in the cylinder wall .11 suchthat the elongated portion thereof is in contact with theelectromagnetic plunger 2, compressed between two springs withrespective repulsive forces acting in the opposite directions to eachother, namely upper and lower springs 9 and 4, respectively, in FIG. 1;intermission of the energizing current to the solenoid coil 1 is made /2of the frequency of variation of the momentary value of the full-waveA-C current by a half-wave rectification system; and the number of thefrequency of reciprocating movement of both plungers 2 and 3 issynchronized with this frequency. Namely, particularly noteworthy arethe following four advantages resulting from the above features: (1)performance of the pump is improved; (2) consumption of electric powerrequired for driving the pump is reduced; (3) burnup-loss of the coil 1is inhibited due to a comparatively limited rise in the temperature ofthe coil; and (4) service life of the pump is increased due to nogeneration of sparks and the elimination of contacts. These advantageswill be discussed in more detail hereinbelow.

Adoption of a half-wave rectification system for interruption of theenergizing current to the coil 1 will, as mentioned above, appreciablyimprove efficiency of the pump since the stroke length of the dischargeplunger 3 is increased compared to that of one using a full-wave A-Csystem.

In other words, the system using a half-wave rectifying current consumesless electricity than the system using a full-wave alternating current,so that, in the former system, there is caused a smaller rise in thetemperature of the coil 1, which results in a small increase inresistance and retardation of a gradual reduction of the pump dischargeoutput which may otherwise be caused by a gradual rise in temperaturedue to the electric current supplied to the coil 1. Consequently areduction of pump performance can be prevented. This is attributable tothe fact that since the magnetic attraction produced by applying anelectric current to the coil 1 is proportional to the square of theamount of the electric current flowing in the coil 1 and to the productof the number of turns of the coil 1, the rise of electric resistancedue to the rise of coil temperature results in a reduction of the amountof electric current flowing in the coil 1, thus weakening the magneticattraction.

Also, the current interruption system utilizing the halfwave rectifyingcurrent is advantageous in that no spark is produced and no wear or lossof contact itself takes place, as compared with the contact system.

Further, since both plungers 2 and 3 are compressed in contactrelationship between the upper and lower springs 9 and 4, when noelectric current is applied to the solenoid coil 1, both plungers 2 and3 remain still at a position where their opposed repusive forces arebalanced, while having the respective amounts of flexibility in inverseproportion to the respective spring constants of the upper and lowersprings 9 and 4.

The magnetic attractive force produced upon energization of the solenoidcoil 1 causes both plungers 2 and 3 to move from the balanced positiontoward the magnetic center, that is, toward the lower part in FIG. 1,and this becomes the pump discharge stroke. Then, when the electriccurrent supply to the solenoid coil 1 is interrupted, both plungers 2and 3 return to their original positions, thus effecting the pumpsuction stroke. During these suction and discharge strokes, both theupper and lower springs 9 and 4 absorb alternately the mass of bothplungers 2 and 3 and the kinetic energy of inertia due to theirvelocity. Namely, they provide bulfer action against shock by increasingtheir flexing, and then immediately thereafter, the absorbed energy isreleased, which results in adding to the repulsive forces of thesprings, the reinforced repulsive forces being synchronized withreciprocating movements of both plungers 2 and 3 to elongate the strokelength, thus bulfering the discharging and suction actions and enhancingpump performances.

It is required that the greater the reciprocating velocity of theplungers 2 and 3, the larger the spring constant of the springs 9 and 4which repeat elongation and contraction in synchronization with thereciprocation of the plungers. This means that the springs used must bestrong. To the contrary, the lower the reciprocating velocity of bothplungers 2 and 3, or the longer the interrupted period of the electriccurrent sent to the solenoid coil 1, the smaller may be the strength ofboth the upper and lower springs.

Thus, according to the half-wave rectification system, the interruptionperiod of the current supplied to the solenoid coil 1 is double that inan A-C full-wave system, and also the frequency per unit time is V2thereof, so that both the upper and lower springs 9 and 4 may becorrespondingly of relatively low strength. This also means that therepulsive force of the lower spring 4 resisting against the magneticattraction produced upon energization of the solenoid coil 1 during thepump discharging operation, may be small, which consequently enablesfull and efficient utilization of the magnetic attractive force duringthe pump operation, as well as, an increase of the pump stroke length,with a resulting enhanced working efficiency and performance of thepump.

Further, since the plungers 2 and 3 are compressed between the upper andlower springs 9 and 4, an increase of internal pressure, or dischargepressure, of the pump results in a corresponding increase in the flexingof the upper spring 9 and its stress, whereby an increment of theinternal pressure is absorbed and the corresponding operating positionsof both plungers 2 and 3 are moved. This elfects a pump dischargeoperation within the range of the magnetic attractive force acting onthe pump, so that even if the discharge side of the pump is closed, itis possible to restrain the internal pressure of the pump within thisrange, thus perfectly eliminating any possibility of a break in ordamage to, the pump.

Further, the present invention employs a free piston type pump arrangedsuch that the stroke length of both plungers 2 and 3 is automaticallyelongated, with the discharge amount being correspondingly increased,when the discharge pressure of the pump is low or when the resistance ofthe fluid passing in the pump is small, so that in case this pump isused, for example, for supplying of fuel oil to a combustion machine orfor spraying purposes, when the oil in the fuel oil tank is emptied, asimple operation of feeding oil into the fuel oil tank will immediatelysuck up and discharge the air in the pipe line connecting the pump andthe oil tank, thus allowing the desired supply of fuel oil or spray.

By adjusting the sum of the amounts of flexing of both upper and lowersprings by turning clockwise or counterclockwise the screw member 12located at a topmost posi-- tion in FIG. 1, it is possible tocorrespondingly adjust the distance between the magnetic plunger 2 andthe magnetic center of the coil 1 and to accordingly adjust theeffective force of the magnetic attraction exerted on theelectromagnetic plunger 2, which capability of the present deviceadjusts and regulates pump discharge pressure and flow rate.

As described above, according to the present invention, theelectromagnetic plunger 2 and the discharge plunger 3 are formed asseparate units and arranged to be in contact, and both plungers arecompressed between the upper and lower springs 9 and 4 arranged such asto work against each other with their respective repulsive forces, andalso a half-wave rectifier is connected in series to the solenoidcoil 1. These three structural conditions combined together provide animproved solenoid type plunger pump which has higher performance, widerversatility in adjustment of discharge pressure and flow rate, andlonger service life than any conventional ones.

I claim:

1. A solenoid type electromagnetic pump comprising a solenoid coil,

an electromagnetic plunger slidably disposed reciprocatingly within thecenter of said solenoid coil,

a separate discharge plunger axially disposed in tandem to and joined tosaid electromagnetic plunger,

an upper spring and a lower spring, between which said electromagneticplunger and said discharge plunger are operatively compressed,respectively,

a half-wave rectifier operatively connected in series with said solenoidcoil,

a plunger casing extending through the center and concentric with saidsolenoid coil,

said electromagnetic plunger slidably disposed inside said plungercasing,

a cylinder wall disposed beneath said electromagnetic plunger, saiddischarge plunger slidably disposed for reciprocation in said cylinderwall,

said discharge plunger disposed below said electromagmetic plunger andhaving an extended top end portion joined to said electromagneticplunger,

said upper and lower springs operating with respective repulsive forcesin opposite directions, and

a screw means abutting the upper end of said upper spring for beingturned to adjust said electromagnetic plunger relative to said solenoidcoil, said upper spring operatively abutting at its bottom end the topof said electromagnetic plunger.

References Cited UNITED STATES PATENTS 2,382,426 8/1945 Kocher 103--533,139,952 7/1964 Jackson 103-53 XR 3,200,591 8/1965 Ray 10353 XR3,250,219 5/ 1966 McCarty et al. 10353 3,394,657 7/ 1968 Sanders et al103--53 ROBERT M. WALKER, Primary Examiner U.S. Cl. X.R.

